A-351 Versatile and Sensitive Microfluidic Immunoassay for Improved Point-of-Care Diagnostics

Background Healthcare professionals must choose between sensitivity and ease-of-use in diagnostics, particularly for diseases like COVID-19 and strep throat. Traditional enzyme-linked immunosorbent assays (ELISAs) are sensitive but are manually intensive and lengthy. Lateral flow assays (LFAs) are an alternative with low cost, ease-of-use, and rapid results; but LFAs suffer from low sensitivity. Burst Diagnostics presents a groundbreaking solution with the capillary-driven immunoassay (CaDI), a novel microfluidic device delivering sensitivity comparable to ELISA with the ease of LFAs. Methods The CaDI is made of flow channels defined by layered transparency and adhesive sheets containing reagent pads with HRP-conjugated antibody and luminol. The system requires only a sample addition step by the user. Sample flow initiates sequential steps of a sandwich ELISA, fully automated by the device, to provide a chemiluminescent signal in 10 minutes or less, depending on sample matrix. Results We have demonstrated success with preliminary studies for the detection of SARS-CoV-2 nucleocapsid protein (NP) and group A streptococcus (GAS). Detection of NP was achieved by assembling and optimizing COVID-19 CaDI’s using anti-NP antibodies. Then, spiked nasal swab samples were tested ranging from 10 to 1000 PFU/mL with positive detection as low as 10 PFU/mL, much less than the same samples in a traditional LFA (see figure). Additionally, we have demonstrated successful detection of GAS in optimized buffer conditions up to 100-fold less than commonly used LFAs. Finally, multiplexed CaDI’s increase throughput and cost-effectiveness in the point-of-care setting. Conclusions The CaDI platform bridges the ease of LFAs and sensitivity/specificity of laboratory tests. Currently, the CaDI can detect SARS-CoV-2 NP and GAS with higher sensitivity than existing LFAs. Development is underway for a reader to accompany the CaDI and further simplify the test. Importantly, the potential targets for detection are immense due to the sensitivity, simplicity, and adaptability of the platform.